Coal blending combustion system with honeycomb type branch pulverized coal bunker

Abstract

The invention relates to the field of coal-fired power generation, and particularly discloses a coal blending and blending combustion system with a honeycomb type branch pulverized coal bunker, which comprises the honeycomb type branch pulverized coal bunker, a powder storage section, a powder feeding section and a control system, the honeycomb type separated pulverized coal bunker comprises a plurality of mutually independent small bunkers and is used for storing pulverized coal with different coal qualities; the powder storage section comprises a powder preparation device, a coal quality on-line monitoring device, a fine powder separation device and a drainage device; the pulverized coal feeding section comprises a pulverized coal feeder, a pulverized coal mixing device and a pulverized coal distributor; in the pulverized coal storage stage, the control system controls the drainage device according to the coal quality information, and pulverized coal of different coal qualities is stored in different small bins; in the pulverized coal feeding stage, the control system controls the pulverized coal feeder according to the operation condition of the coal-fired unit, pulverized coal in the corresponding small bins is fed into the pulverized coal mixing device to be mixed, and the discharging flow of the pulverized coal feeding stage is controlled. The method has the effects that the deep and rapid peak regulation capacity of the boiler is improved, the operation economy and stability of the coal mill are improved, and the combustion economy and environment friendliness of the boiler are improved.

Description

Technical Field

[0001] The present application relates to the field of coal-fired power generation, and in particular to a coal blending and combustion system having a honeycomb-type pulverized coal bin. Background Art

[0002] At present, with the large-scale grid connection and consumption of new energy sources with large fluctuations and prominent intermittentity, such as wind energy and solar energy, the proportion of new energy power sources in the power grid has increased significantly, and the problem of unstable load in the power grid has become prominent. In order to maintain the stable operation of the power grid, coal-fired power generation, as the only flexible resource that can achieve large-scale economic deep and rapid peak regulation, plays an important role as a ballast and regulator for the stability of the power grid. Therefore, improving the flexibility of coal-fired power generation units is one of the urgent needs of new energy hybrid power grids. The flexibility of coal-fired power units requires that the boiler can burn stably under low load conditions and can respond quickly to combustion under variable load conditions.

[0003] However, for boilers with direct-blowing pulverizing systems, during load changes, the pulverizing process is required to deliver pulverized coal into the furnace to achieve changes in the amount of fuel, resulting in slow system load adaptability, low efficiency in eliminating internal disturbances, and large fluctuations in steam pressure, which seriously restricts the flexibility of the boiler. In addition, since low-load stable combustion of boilers requires high coal quality, and most power plants in my country burn mixed coal, the quality of coal entering the furnace varies greatly, making low-load stable combustion difficult. At the same time, the quality of coal entering the furnace often deviates from the optimal coal quality corresponding to the boiler load, resulting in problems such as poor boiler economy, unstable combustion, and high pollutant emissions. Summary of the invention

[0004] In order to improve the problem of slow load response in the direct-blowing pulverizing system, adapt to changes in the quality of coal entering the furnace, improve the economy and combustion stability of the boiler, and reduce pollutant emissions, the present application provides a coal blending and combustion system with a honeycomb-type pulverized coal bin.

[0005] The present application provides a coal blending and combustion system with a honeycomb-type coal powder storage bin, which adopts the following technical solution: A coal blending and burning system with a honeycomb-type coal powder storage bin, comprising: The honeycomb-type coal powder bin includes a plurality of independent small bins, each of which is used to store coal powders of different coal qualities; The powder storage section includes a powder making device, a coal quality online monitoring device and a fine powder separation device which are sequentially arranged along the coal powder conveying direction, and a drainage device is arranged at the discharge end of the fine powder separation device; The powder delivery section includes a powder feeder, a coal powder mixing device and a coal powder distributor which are sequentially arranged along the coal powder conveying direction, wherein the powder feeder is installed at the discharge end of each of the small bins in a one-to-one correspondence, and the feed end of the coal powder mixing device is simultaneously connected to the discharge ends of multiple powder feeders; The control system controls the drainage device according to the coal quality information during the powder storage stage, and drains the coal powder of different coal qualities to different small bins for storage; during the powder delivery stage, the powder feeder is controlled according to the operation status of the coal-fired unit, and the coal powder in the corresponding small bin is sent to the coal powder mixing device for mixing, and the discharge flow rate of the powder delivery section is controlled.

[0006] Furthermore, the drainage device includes a multi-way valve and a plurality of drainage pipes, and the discharge ends of the plurality of drainage pipes correspond one-to-one to the plurality of small bins.

[0007] Furthermore, the powder storage section also includes a flow regulating device.

[0008] Furthermore, the feed end of the pulverized coal mixing device is connected to a pulverized coal conveying air source.

[0009] Furthermore, the discharge end of the pulverized coal distributor is divided into multiple pipelines, which are respectively connected to the boiler burner or the independent burner.

[0010] The coal blending and combustion system provided in this application is divided into the powder storage stage and the powder delivery stage when working: In the powder storage stage, coal powder is prepared by a powder making device, and the coal powder flow in the powder storage section is adjusted by a flow regulating device. The coal powder enters the fine powder separation device after coal quality testing by an online coal quality monitoring device. The control system controls the steering of the multi-way valve according to the coal quality information, so that the coal powder output by the fine powder separation device enters different drainage pipes, thereby draining coal powder of different coal qualities into different small bins for storage.

[0011] During the powder delivery stage, the control system obtains the optimal coal quality ratio and flow rate of the coal powder according to the operation status of the coal-fired unit, and then controls the powder feeder to send the coal powder in the corresponding small bin into the coal powder mixing device for mixing. At the same time, the control system controls the powder delivery air source to adjust the discharge flow rate of the powder delivery section; the mixed coal powder enters the pulverizing device, boiler burner or independent burner through the coal powder distributor.

[0012] When the boiler quickly increases or decreases load, the honeycomb-type pulverized coal bin is used to deliver and store pulverized coal to enhance the load increase and decrease capacity; under low load conditions, the honeycomb-type pulverized coal bin delivers high-quality pulverized coal into the furnace to improve the boiler's low-load stable combustion capacity. On the other hand, the pulverized coal delivery section delivers pulverized coal of suitable quality into the burner to achieve mixed combustion in the pulverized coal furnace. The mixed pulverized coal can achieve the optimal pulverized coal flow and quality under the load, improve the boiler's economy and combustion stability, and reduce pollutant emissions.

[0013] Furthermore, the pulverizing device includes one or two coal mills.

[0014] When both coal mills are operating at partial load, only one coal mill can be operated, and the other coal mill can be replaced by the honeycomb-type pulverized coal bin to deliver pulverized coal to the boiler. The coal mill output can also be increased by storing pulverized coal in the honeycomb-type pulverized coal bin to avoid low-load operation of the coal mill, thereby improving the economy and stability of coal mill operation.

[0015] Furthermore, the plurality of small bins are arranged in an array or a honeycomb-shaped row, and partitions are provided between adjacent small bins.

[0016] In this way, centralized storage and management of coal powder is achieved, saving space; coal powder of different coal qualities is stored in different small warehouses, which facilitates the flexible transportation and blending of coal powder according to actual conditions.

[0017] Furthermore, the exhaust gas outlet of the fine powder separation device is connected to the boiler SOFA tuyere or burner.

[0018] The present application also provides a coal blending and combustion control method for a coal-fired unit, using a coal blending and combustion system with a honeycomb-type coal powder bin, the method comprising the following steps: Powder storage stage: The coal quality online monitoring device detects the coal quality output by the pulverizing device. After the coal powder passes through the fine powder separation device, the control system controls the drainage device according to the coal quality information to store the coal powder of different qualities in different small bins; Powder delivery stage: The control system selects pulverized coal of suitable quality according to the operation status of the coal-fired unit and controls the corresponding powder feeder to deliver the pulverized coal in the corresponding small bin into the pulverized coal mixing device for mixing; at the same time, the control system controls the discharge flow rate of the powder delivery section and delivers the mixed pulverized coal into the coal-fired unit for blending.

[0019] Furthermore, the method for obtaining the operating conditions of the coal-fired unit is: measuring and recording the parameters of the coal-fired unit, including: flue gas volume, exhaust temperature, pollutant type and content; and obtaining the residence time, operating temperature range, flow and reaction process of the pollutants in the boiler by analyzing the parameters of the coal-fired unit.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. The honeycomb-type pulverized coal bin realizes the centralized storage and management of pulverized coal, saves space, and can realize flexible transportation and blending according to actual conditions, improve the burnout rate, and reduce pollutant emissions; 2. Improve the deep and rapid peak-shaving capability of the boiler: When the boiler rapidly increases or decreases the load, the honeycomb-type pulverized coal bin is used to deliver and store pulverized coal to enhance the load-increasing and load-reducing capabilities, so as to improve the problem of slow load response in the direct-blowing pulverizing system. Under low-load conditions, high-quality pulverized coal is delivered into the furnace from the honeycomb-type pulverized coal bin, so as to improve the low-load stable combustion capability of the boiler. 3. Improve the economical and stable operation of coal mills: When both coal mills are operating at partial load, only one coal mill can be operated, and the other coal mill can be replaced by sending coal powder from the honeycomb-type coal powder bin to the boiler. The output of the coal mill can also be increased by storing coal powder in the honeycomb-type coal powder bin to avoid low-load operation of the coal mill; 4. Improve the combustion economy and environmental protection of the boiler: According to the boiler load and the quality of the coal entering the furnace, open the powder storage section, store the pulverized coal in the corresponding small bin according to the coal quality information, and at the same time open the powder delivery section to deliver pulverized coal of suitable quality into the burner to achieve mixed combustion in the pulverized coal furnace. The mixed pulverized coal can achieve the optimal pulverized coal flow and quality under the load, improve the economy and combustion stability of the boiler, and reduce pollutant emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of a coal blending and combustion system with a honeycomb-type pulverized coal bin in an embodiment of the present application; Figure 2 This is a schematic diagram of a coal blending and combustion system with a honeycomb-type pulverized coal bin for an existing unit according to Example 1 of the present application; Figure 3 This is a schematic diagram of a coal blending and combustion system with a honeycomb-type pulverized coal bin for use in a newly built unit according to Example 2 of the present application.

[0022] Figure numerals: 1. Coal mill; 2. Electric valve; 3. Electric adjustable shrinkage hole; 4. Coal quality online monitoring device; 5. Cyclone separator; 6. Air lock; 7. Drainage device; 701. Drainage pipe; 702. Three-way valve; 8. Honeycomb-type pulverized coal bin; 801. Small bin; 802. Partition; 803. Explosion-proof door; 9. Pneumatic plug-in door; 10. Powder feeder; 11. Electric damper; 12. Pulverized coal mixer; 13. Pulverized coal distributor; 14. Boiler burner; 15. Boiler SOFA air outlet; 16. Boiler; 17. Independent burner. DETAILED DESCRIPTION

[0023] The following is combined with Figure 1-3 This application is described in further detail.

[0024] The present application embodiment discloses a coal blending and burning system with a honeycomb type coal powder storage bin. Figure 1 , Figure 2 and Figure 3 The coal blending and combustion system with a honeycomb-type coal powder bin includes a powder storage section, a honeycomb-type coal powder bin 8 and a powder delivery section arranged in sequence along the coal powder conveying direction, and also includes a control system.

[0025] Reference Figure 1The honeycomb-type coal powder storage bin 8 includes a plurality of independent small bins 801, each of which is used to store coal powder of different qualities. The plurality of small bins 801 are arranged in an array or honeycomb shape, and partitions 802 are provided between adjacent small bins 801 to achieve classified storage of coal powder.

[0026] Each small warehouse 801 is equipped with an oxygen concentration sensor and a temperature measuring device, and is equipped with a moisture absorption and drying system, a fire inerting system, a heat preservation system, and anti-blocking measures to ensure the safe and stable operation of the system. The honeycomb-type coal powder warehouse 8 can achieve precise temperature control in each small warehouse 801. Small warehouses 801 with different coal qualities can be equipped with explosion-proof measures according to actual conditions, such as Figure 1 As shown, an explosion-proof door 803 can be used to improve system safety and reliability.

[0027] Reference Figure 1 , Figure 2 and Figure 3 The powder storage section includes a powder making device, a coal quality online monitoring device 4 and a fine powder separation device arranged in sequence along the coal powder conveying direction. Among them, the powder making device is a coal mill 1, and the fine powder separation device is a cyclone separator 5. The powder storage section is also provided with a flow regulating device, including an electric valve 2 and an electric adjustable shrinkage hole 3 arranged at the discharge end of the coal mill 1.

[0028] Reference Figure 1 , Figure 2 and Figure 3 The discharge end of the cyclone separator 5 is provided with an air lock 6 and a drainage device 7 in sequence, including a three-way valve 702 and a plurality of drainage pipes 701, and the discharge ends of the plurality of drainage pipes 701 correspond one by one to the plurality of small bins 801. The exhaust gas outlet of the cyclone separator 5 can be connected to the boiler SOFA tuyere or burner.

[0029] Reference Figure 1 , Figure 2 and Figure 3 The powder delivery section includes a powder feeder 10, a coal powder mixer 12 and a coal powder distributor 13 which are arranged in sequence along the coal powder conveying direction. The powder feeder 10 is installed at the discharge end of each small bin 801 in a one-to-one correspondence, and a pneumatic gate 9 is installed between the small bin 801 and the powder feeder 10. The coal powder mixer 12 is provided with a plurality of feed ports, each of which is connected to the discharge end of each powder feeder 10. The feed end of the coal powder mixer 12 is connected to a powder delivery air source, and an electric damper 11 is installed at the air outlet end of the powder delivery air source. The powder delivery air source is a mixed air of the cold and hot primary air main pipes, or an air source provided by a separate fan, and the air source temperature is 60-150 degrees Celsius.

[0030] Further, refer to Figure 1 , Figure 2 and Figure 3The discharge end of the pulverized coal distributor 13 is divided into multiple pipelines, which are respectively connected to the boiler burner 14 or the independent burner 17.

[0031] The electric valve 2, the three-way valve 702, the powder feeder 10, and the powder delivery air source are all installed with control components, and each control component and the coal quality online monitoring device 4 are integrated into the control system.

[0032] The implementation principle of a coal blending and burning system with a honeycomb-type coal powder storage bin in the embodiment of the present application is as follows: In the powder storage stage, coal powder is prepared by the coal mill 1, and the coal powder flow in the powder storage section is adjusted by the electric valve 2 and the electric adjustable shrinkage hole 3. The coal powder enters the cyclone separator 5 after the coal quality is tested by the coal quality online monitoring device 4; the control system controls the steering of the multi-way valve according to the coal quality information, so that the coal powder output from the cyclone separator 5 enters different drainage pipes 701, thereby draining the coal powder of different coal qualities into different small bins 801 for storage.

[0033] During the operation of the coal-fired unit, the parameters of the coal-fired unit are measured and recorded, including the flue gas volume, exhaust gas temperature, pollutant type and content; the residence time, operating temperature range, flow and reaction process of the pollutants in the boiler 16 are obtained from the parameter analysis of the coal-fired unit.

[0034] During the powder delivery stage, the control system obtains the optimal coal quality ratio and flow rate of the coal powder according to the operation status of the coal-fired unit, and then controls the powder feeder 10 to deliver the coal powder in the corresponding small bin 801 into the coal powder mixer 12 for mixing. At the same time, the control system controls the powder delivery air source to adjust the discharge flow rate of the powder delivery section; the mixed coal powder enters the burner through the coal powder distributor 13 to achieve mixing and co-combustion.

[0035] When the boiler 16 rapidly increases or decreases the load, the honeycomb-type pulverized coal bin 8 is used to deliver and store pulverized coal to enhance the load-increasing and load-reducing capabilities, so as to improve the problem of slow load response in the direct-blowing pulverizing system. Specifically, when the boiler 16 rapidly increases the load, the pulverized coal delivery condition is started, and pulverized coal is delivered through the honeycomb-type pulverized coal bin 8 to improve the load-increasing capacity; when the boiler 16 rapidly decreases the load, the pulverized coal storage condition is started, and part of the pulverized coal output by the coal mill 1 is input into the honeycomb-type pulverized coal bin 8 for storage, so as to improve the load-reducing capacity. Under low-load conditions, high-quality pulverized coal is delivered into the furnace by the honeycomb-type pulverized coal bin 8, thereby improving the low-load stable combustion capability of the boiler 16.

[0036] On the other hand, the powder delivery section delivers pulverized coal of suitable quality into the burner to achieve mixed combustion in the pulverized coal furnace. The mixed pulverized coal can achieve the optimal pulverized coal flow and quality under the load, improve the economy and combustion stability of the boiler 16, and reduce pollutant emissions.

[0037] The following is a specific example of how to use the above-mentioned coal blending and combustion system with honeycomb-type pulverized coal bins in an existing unit or a newly built unit: Example 1 For existing units, refer to Figure 2 The powder delivery pipe near the mill of the original coal mill 1 is opened as the entrance of the powder storage section; the powder delivery pipe near the furnace is opened as the outlet of the powder delivery section. The honeycomb type coal powder storage bin 8 includes two small bins 801, which are used to store high-quality coal powder and ordinary coal powder respectively. The exhaust gas of the fine powder separator enters the boiler SOFA air inlet 15.

[0038] In the powder storage stage, the powder delivery section does not work, and the powder storage section stores the coal powder of different coal qualities into two small bins 801. The powder storage condition can be turned on when the boiler 16 is rapidly unloaded, so that the coal powder enters the honeycomb-type sub-bin coal powder bin 8 for storage to avoid entering the furnace; it can also work when the output of a single coal mill 1 is small and the economy is poor, and the output of the coal mill 1 is appropriately increased, so that the excess coal powder enters the honeycomb-type sub-bin coal powder bin 8 for storage to improve the output economy of the coal mill 1.

[0039] During the powder delivery stage, the powder storage section does not work. The powder delivery air is drawn from the mixed air of the original boiler's cold and hot primary air main pipes. The coal powder in the honeycomb-type coal powder bin 8 is evenly delivered to the powder delivery pipeline of the burner on the same layer through the coal powder distributor 13. The powder delivery condition is used to improve the stable combustion capability during the load change process of the boiler 16. When the boiler 16 increases the load quickly, the powder delivery section is controlled to deliver powder to make up for the insufficient output of the coal mill 1 at the initial stage of the load change; when the boiler 16 is under low load, in order to ensure stable combustion, the high-quality coal powder small bin 801 is controlled to deliver powder into the furnace for mixed combustion to improve the combustion efficiency in the furnace.

[0040] Example 2 For new units, refer to Figure 3 , a honeycomb type coal powder storage and coal blending system is added to the two coal mills. The inlet of the powder storage section is drawn from the newly added powder outlet of the two coal mills 1, and the powder delivery air of the powder delivery section comes from the newly added powder delivery fan. Similar to Example 1, the working conditions of Example 2 are also divided into a powder storage stage and a powder delivery stage. The exhaust gas under the powder storage condition and the coal powder under the powder delivery condition both enter the independent burner 17 arranged between the two layers of boiler burners 14.

[0041] When both coal mills 1 are operating at partial load, only one coal mill 1 can be operated, and the other coal mill 1 can be replaced by the honeycomb-type pulverized coal bin 8 to deliver pulverized coal to the boiler 16. The output of the coal mill 1 can also be increased by storing pulverized coal in the honeycomb-type pulverized coal bin 8 to avoid low-load operation of the coal mill 1, thereby improving the operating economy and stability of the coal mill 1.

[0042] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A coal blending and burning system with honeycomb-type coal powder storage bins, characterized in that: include: The honeycomb-type coal powder bin includes a plurality of independent small bins, each of which is used to store coal powders of different coal qualities; The powder storage section includes a powder making device, a coal quality online monitoring device and a fine powder separation device which are sequentially arranged along the coal powder conveying direction, and a drainage device is arranged at the discharge end of the fine powder separation device; The powder delivery section includes a powder feeder, a coal powder mixing device and a coal powder distributor which are sequentially arranged along the coal powder conveying direction, wherein the powder feeder is installed at the discharge end of each of the small bins in a one-to-one correspondence, and the feed end of the coal powder mixing device is simultaneously connected to the discharge ends of multiple powder feeders; The control system controls the drainage device according to the coal quality information during the powder storage stage, and drains the coal powder of different coal qualities to different small bins for storage; during the powder delivery stage, the powder feeder is controlled according to the operation status of the coal-fired unit, and the coal powder in the corresponding small bin is sent to the coal powder mixing device for mixing, and the discharge flow rate of the powder delivery section is controlled.

2. A coal blending and combustion system with honeycomb-type coal powder storage bins according to claim 1, characterized in that: The pulverizing device comprises one or two coal mills.

3. The coal blending and combustion system with honeycomb-type coal powder storage bins according to claim 1 is characterized in that: The drainage device includes a multi-way valve and a plurality of drainage pipes, and the discharge ends of the plurality of drainage pipes correspond one by one to the plurality of small bins.

4. The coal blending and combustion system with honeycomb-type coal powder storage bins according to claim 1 is characterized in that: The powder storage section also includes a flow regulating device.

5. The coal blending and combustion system with honeycomb-type coal powder storage bins according to claim 1 is characterized in that: The feed end of the pulverized coal mixing device is connected to a pulverized coal conveying air source.

6. The coal blending and burning system with honeycomb-type coal powder storage bins according to claim 1, characterized in that: The discharge end of the pulverized coal distributor is divided into multiple pipelines, which are respectively connected to the boiler burner or the independent burner.

7. The coal blending and combustion system with honeycomb-type coal powder storage bins according to claim 1 is characterized in that: The plurality of small bins are arranged in an array or a honeycomb row, and partitions are provided between adjacent small bins.

8. The coal blending and combustion system with honeycomb-type coal powder storage bins according to claim 1, characterized in that: The exhaust gas outlet of the fine powder separation device is connected to the boiler SOFA tuyere or burner.

9. A method for controlling coal blending and combustion of a coal-fired unit, characterized in that: A coal blending and burning system with a honeycomb-type pulverized coal bin as described in any one of claims 1 to 8 is used, and the method comprises the following steps: Powder storage stage: The coal quality online monitoring device detects the coal quality output by the pulverizing device. After the coal powder passes through the fine powder separation device, the control system controls the drainage device according to the coal quality information to store the coal powder of different qualities in different small bins; Powder delivery stage: The control system selects pulverized coal of suitable quality according to the operation status of the coal-fired unit and controls the corresponding powder feeder to deliver the pulverized coal in the corresponding small bin into the pulverized coal mixing device for mixing; at the same time, the control system controls the discharge flow rate of the powder delivery section and delivers the mixed pulverized coal into the coal-fired unit for blending.

10. A method for controlling coal blending and combustion of a coal-fired unit according to claim 9, characterized in that: The method for obtaining the operating conditions of the coal-fired unit is: measuring and recording the parameters of the coal-fired unit, including: flue gas volume, exhaust temperature, pollutant type and content; and obtaining the residence time, operating temperature range, flow and reaction process of the pollutants in the boiler by analyzing the parameters of the coal-fired unit.

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